Attachment for heating apparatus



Nov. 10, 1936. A. H. SENNER' 3 ATTACHMENT FOR HEATING APPARATUS Filed July 10, 1935 Fig. 4

Patented Nov. 10, 1936 UNITED STATES PATENT OFFICE Arthur H. Senncr, Baltimore, Md., dedicated to the free use of the Public Application July 10,

7 Claims.

1935, Serial No. 30,694

(Granted under the act of March 3, 1883, as

amended April 30,

This application is made under the act of March 3, 1883, as amended by the act of April 30, 1928, and the invention herein described may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

I hereby dedicate the invention herein described to the free use of the public, to take effect upon the granting of a patent to me.

My invention relates to improvements in heating apparatus of the combustion type and more .lespecially in heating apparatus designed for burning solid. fuels but which are to be converted and adapted for burning liquid or gaseous fuel.

Some types of heating apparatus designed for burning coal and which have provided reasonably satisfactory performance when burning that fuel have failed to develop the required heating capacity or have been found wasteful of fuel, when equipped for burning oil fuel. This applies to heating apparatus having adequate grate surface but where flue passages, through which the products of combustion pass on the Way to the chimney, are relatively short and direct and afford relatively small heat absorbing area in contact with the hot flue gases. This condition is found in cast iron heating boilers of the sectional type, designed for burning coal commonly employed for heating purposes, where, either to adapt the boiler to conditions of limited draft, or for economy in first cost, the number of; sections employed in making up the boiler, has been limited to the least number which are required to make up a complete boiler, reducing the length and area of the flues to a minimum.

Heat liberated in a heating apparatus by combustion of fuel is transmitted to the walls of the combustion chamber and fiues by similar processes when either solid or liquid fuels are being burned, but, owing to properties inherent in the fuels themselves, the gaseous products of combustion leaving the combustion chamber will be at. a. higher. temperature when burning oil than when coal is being burned, with equal rates of heat production in the same heating apparatus. The thermal contact between burning fuel and firepot wall when burning. oil is that of gas to solid and affords a lower rate of heat transfer by conduction than the contact between the solid incandescent coal bed and flrepot. Less heat is also radiated from the oil flame, since the radiant portion of the flame presents less radiating area and is at a greater distance from heat absorbing surfaces than the coal bed. The longer flame of the oil makes it necessary to so locate the oil and air nozzles that combustion will be substantially complete before the flame impinges against heat absorbing surfaces which would chill it below combustion temperature, and result in formation of smoke and soot.

The lesser amount of heat conducted and radiated to the walls of the combustion chamber by the oil flame leaves a larger proportion of the generated heat to be carried away by the flue gases issuing from the chamber and the flue gases therefore with oil fuel are heated to a higher temperature than with coal. When oil is burned in heating apparatus having short and direct flue passages which do not afford sufiicient flue wall surface for adequate absorption of the heat carried by the hotter flue gases, the gases leave the heating apparatus at an unduly high temperature and carry an excessive amount of wasted heat up the chimney. The conversion of heating apparatus of this character to oil burning necessarily results in reduced capacity and efliciency.

I overcome the objections cited above by means of the invention hereinafter described and illustrated in the accompanying drawing, in which Fig. 1 is a top view of a typical form of my attachment as arranged for application to one type of conventional coal burning furnace; Fig. 2 is a bottom view, Fig. 3 is a vertical section on line 3-3 and Fig. 4 is a vertical section on the line 4-4 of Fig. 2, of the attachment installed in a conventional heating fur nace.

Similar figures of reference refer to the same parts in each of the several figures.

My invention consists of an attachment adapted to be installed in the flue passages of furnaces, boilers or other forms of combustion heating apparatus. The drawing, Figures 1 to 4 inclusive, shows my invention adapted to the flue passages of a conventional type of heating boiler having a single central circular opening I from the top of the combustion chamber 2 into the flue chamber 3 above, and four equally spaced outlet openings 4 from flue chamber 3 into the smoke bonnet 5 above. My attachment is installed in flue chamber 3, covering the opening I and extending radially outward therefrom.

The attachment comprises a plurality of similar sections 6, the number of such sections corresponding to the number of outlet openings 4, which in this case is four. The inner end of each section is in, the form of a wedge having an included angle of such dimension that the several sections when assembled in position in the furnace, completely cover the opening I. The attachment would function in exactly the same manner if the several sections were combined to form an integral unit. The sectional construction is provided, for convenience in installation. Each section 6 comprises a series of baffles I, formed integrally with a base plate 8 and a cover plate 9. The base plate 8 extends only under those portions of the baffles I which lie outside of the opening I of the furnace and does not extend over opening I. The cover plate 9 extends the entire length of the baffles I. The base plate 8 of each section is secured to the adjacent flue wall I0 of the flue chamber by metallic cement II of high thermal conductivity. The bafiles I, base plate 8 and cover plate 9 enclose a series of flue passages I2 extending outwardly from the central opening I and terminating near the outer wall I3 of the flue chamber 3.

In operation the hot gaseous products of combustion rising through the opening I enter the flue passages I2 and pass outward through the same and, on issuing from the outer ends of these passages are directed against the outer walls I3 of flue chamber 3. The combined cross sectional area of flue passages I2 is less than the cross sectional area of chamber 3 through which the gases would pass directly if the attachment were not used. The velocity of the flue gases passing through the passages I2 is increased, due to the restricted area of the passages. The increased velocity of the gases in these passages provides a higher rate of heat transfer from the hot gases to the walls of the passages I2 and, together with the extended surface presented to contact with the gases by the plurality of bafiies I. base plates 8, and cover plates 9, results in greater total heat absorption from the hot flue gases than would obtain if the attachment were not used. The heat absorbed from the hot gases by baffles I, base plates 8 and cover plates 9 is conducted through the heat conducting metallic cement I I to the wall I I] of flue chamber 3. A further increase in heat absorption is due to the increased velocity with which the hot gases issuing from the flue passages I2 are directed against the side walls I3 of the chamber 3, resulting in greater scrubbing action of the gases upon the flue walls I3 and a higher rate of heat transfer at these points. The pressure head necessary to set up the increased flue gas velocity in the flue passages I2 is supplied by the chimney draft. An excess of draft is available in heating apparatus converted from coal burning to oil burning, owing to the fact that, when oil is being burned, there is no fuel bed resistance to be overcome by the chimney draft, as is the case when solid fuel is being burned.

While I have illustrated and described my invention as adapted for a heating apparatus of a particular type having a single outlet from the combustion chamber to a flue chamber located directly above it and having four outlets from the flue chamber, and with my attachment arranged in four similar sections; it is evident that my invention could be readily adapted to the flue passages of heating apparatus of other designs having one or more outlets from the combustion chamber and having a greater or less number of outlets from the flue chamber in which the attachment is installed, and with the attachment itself constructed in a greater or less number of either similar or diss m lar sections as might be required to adapt the attachment to the flue of the particular heating apparatus: without departing from the essential principles of my invention.

I am aware that, prior to my invention, baffles and deflectors have been employed in flue passages of combustion apparatus and that heat absorbing members of various forms have been attached to the walls of combustion chambers and flue passages of such apparatus. I, therefore, do not claim such devices broadly.

I claim:

1. An attachment for combustion-type heating apparatus, comprising a base plate, a cover plate adapted to extend parallel to said base plate and spaced therefrom, a plurality of parallel spaced bafiies formed integrally with said base plate and said cover plate, and adapted to extend perpendicularly thereto and with said bafiies adapted to extend at one end beyond the end of said base plate, said cover plate adapted to extend substantially the entire length of said baffles, said extended portions of said baflies and the adjacent portion of said cover plate adapted to form a symmetrical wedge-shaped portion having an included angle between the converging sides thereof, which is adapted to form an aliquot portion of a circle.

2. In a combustion-type heating apparatus, the combination with a flue of said apparatus of a base plate disposed within said flue and in juxtaposition to a heat-absorbing surface thereof and adapted to extend parallel thereto, a cover plate adapted to extend parallel to said base plate and spaced therefrom, a plurality of parallel spaced bafiies integrally formed with said base plate and said cover plate and adapted to extend perpendicularly thereto and adapted to enclose together therewith a plurality of passages open at each end, heat-conducting cement adapted to join said base plate to said heat-absorbing surface, means for directing gaseous products of combustion evolved in said heating apparatus into one end of each of said passages enclosed between said baflies.

3. In a flue having a horizontal portion and a vertically disposed portion, heat transfer units, each unit including a base plate contacting with the wall of the horizontal portion of the flue, parallel spaced ribs formed integral with the base plate and projecting over the vertical portion of the flue, a top plate attached to said ribs, said top plate being disposed so as to direct the gases passing through the flue along the ribs whereby said ribs are heated and heat transferred through the base plate to the wall of the flue.

4. In a flue having a horizontal portion and a vertically disposed portion, heat transfer units, each unit including a base plate cemented to the wall of the horizontal portion of the flue, parallel spaced ribs formed integral with the base plate and projecting over the vertical portion of the flue, said heat transfer units being arranged in pairs opposed to each other with the edges in contact.

5. In a flue having a horizontal portion and a vertically disposed portion, heat transfer units, each unit including a base plate cemented to the wall of the horizontal portion of the flue, parallel spaced ribs formed integral with the base plate and projecting over the vertical portion of the flue, a top plate attached to said ribs, said top plate being disposed so as to direct the gases passing through the flue along the ribs, said transfer units being arranged in pairs opposed to each other and having their edges meeting.

6. In a flue having a horizontal portion and a vertically disposed portion, heat transfer units, each unit including a base plate cemented to the wall of the horizontal portion of the flue, parallel spaced ribs formed integral with the base plate and projecting over the vertical portion of the flue, a top plate attached to said ribs, said top plate being disposed so as to direct the gases passing through the flue along the ribs, said transfer units being arranged in pairs opposed to each other with the edges of said top plates contacting so as to direct the gases passing up through the vertical flue outward along the ribs whereby the ribs are heated and the heat transferred through the base plate to the wall of the flue.

7. In combination, a flue having a horizontal portion and a vertical portion, heat transfer units disposed in said horizontal portion, each unit including a base plate contacting with the wall of the horizontal portion of the flue and terminating at the edge of the vertical portion of the flue, parallel ribs carried by said base plate and projecting over said flue, said heat units being arranged in pairs opposed to each other, with the ribs of one pair extending at right angles to the ribs of the other pair and with the ends of the ribs meeting on lines extending diametrically of the vertical portion of the flue, a top plate attached to the ribs of each unit and extending over the entire extent of the ribs for directing the heat passing up through the vertical portion of the flue outwardly along the ribs to the outer ends thereof whereby the ribs are heated and the heat transferred through the base plate to the wall of the horizontal portion of the flue.

ARTHUR H. SENNER. 

